@formatjs/ecma402-abstract/NumberFormat/ApplyUnsignedRoundingMode.js

A collection of implementation for ECMAScript abstract operations

import "../types/number.js";
import { invariant } from "../utils.js";
export function ApplyUnsignedRoundingMode(x, r1, r2, unsignedRoundingMode) {
	// If x equals r1 or if r1 equals r2 (already at rounding boundary), return r1
	if (x.eq(r1) || r1.eq(r2)) return r1;
	// If x equals r2, return r2
	if (x.eq(r2)) return r2;
	invariant(r1.lessThan(x) && x.lessThan(r2), `x should be between r1 and r2 but x=${x}, r1=${r1}, r2=${r2}`);
	if (unsignedRoundingMode === "zero") {
		return r1;
	}
	if (unsignedRoundingMode === "infinity") {
		return r2;
	}
	const d1 = x.minus(r1);
	const d2 = r2.minus(x);
	if (d1.lessThan(d2)) {
		return r1;
	}
	if (d2.lessThan(d1)) {
		return r2;
	}
	invariant(d1.eq(d2), "d1 should be equal to d2");
	if (unsignedRoundingMode === "half-zero") {
		return r1;
	}
	if (unsignedRoundingMode === "half-infinity") {
		return r2;
	}
	invariant(unsignedRoundingMode === "half-even", "unsignedRoundingMode should be half-even");
	const cardinality = r1.div(r2.minus(r1)).mod(2);
	if (cardinality.isZero()) {
		return r1;
	}
	return r2;
}